X-Wing (ML-KEM-768 + X25519) hybrid key encapsulation, wrapping
Apple's CryptoKit XWingMLKEM768X25519 native primitive.

What shipped:
  - KeyEncapsulation protocol (parallel of Encryption for KEMs)
  - Tier1/HybridKEM.swift — Aegis's first post-quantum algorithm
  - Package.swift platforms bumped to iOS 26 / macOS 26
  - CI moved to macos-26 (Xcode 26.2, GA on GitHub-hosted runners)
  - 25 NIST FIPS 203 KeyGen KATs passing (mirrored from BoringSSL)
  - 3 X-Wing draft KATs passing (KeyGen + Decap x 2 paths)

Conscious deviation: shipped Apple's X-Wing primitive in place of
the originally-planned concat+HKDF combiner. Rationale, trade-offs,
and approval recorded in docs/STAGES.md v0.0.3.

Test status: 51 tests, 3 skipped (issue #1), 0 failures.

pre-council-approval (Maintainer @DemigodDSK, 2026-04-27)